Field of the Invention
In general, the present invention relates to infrastructure and methods for the analysis of flow in pipe systems. In a preferred form, the infrastructure and methods account for energy status of a sensor device and wear cost functions.
Description of the Relevant Art
Recent technological advancements in the realm of IoT and wireless communication make it feasible to design pipe infrastructures that extend across large geographic areas for automated control and monitoring. While digital control has been integrated into the designs of spatially constrained pipe installations for a long time, for instance in factories and chemical processing plants, enabling it for geographically distributed pipe systems is challenging. Control and monitoring devices often need to be installed at locations without access to the electric grid, requiring such devices to function autonomously, on a small energy footprint.
Presently, many efforts are underway to upgrade water meters in municipal water supply systems with so called smart meters. A smart meter is a digitally enabled flow meter, that presents the measured throughput and possibly other data in digital format, is capable of transmitting data by means of a network and enabled for communication and coordination of actions with a management system. Adoption of smart meter technologies though is slow for several reasons, one of them being the lack of maturity of many aspects of IoT technologies. A legacy flow meter, working on a purely mechanical basis, typically has an expected lifespan of 15 years or more. Many electronic components in IoT device fall short of these lifetimes, more so if deployed outdoors, in harsh climate conditions. For instance, a rechargeable Lithium-ion battery has an expected lifetime of three years in hot climates, whereby the temperature exposure is the main factor for battery aging, rather than the number of recharge cycles. Using rewriteable memory or storage devices with a maximum number of program-erase cycles, such as SSD storage devices, requires careful design, to avoid premature wear. Short lifespans of many components, limiting the overall lifetime of the device, or increasing maintenance costs, are one reason for the slow adoption of smart meters. The cost versus benefit analysis presently is not in favor of them.
A legacy flow meter is a flow meter that does not have a digital interface or if it has one, its capabilities does not satisfy the requirements for integration into a system for the management of smart meters. For instance, a flow meter that functions on a purely mechanical basis, or a flow meter that has a digital interface but no capabilities for long range data transmission by means of a network are regarded as legacy flow meters. See U.S. Pat. App., “Retrofit Device and Method of Retrofitting a Flow Meter” filed concurrently herewith (Att. Dock. #5654-0601) (incorporated by reference). This “Retrofit Device” patent application presents the design of a retrofit device for a legacy flow meter, to enable a legacy flow meter with a mean to digitally represent and transmit measurement data. Aside from the cumulative throughput since installation, typically presented on a flow meter, the retrofit device provides the current rate of flow and is equipped with sensors to collect additional measurement data, such as vibration signals measured in proximity of the pipe envelope.
Retrofit devices reduce the adoption cost for smart meter technology, since equipping a legacy flow meter with a retrofit device avoids the costs associated with replacing that flow meter, which would requires interrupting a pipe. Also, retrofit devices reduce the risk associated with the introduction of new technology. In case of a premature failure of a device, replacement costs are smaller, and, moreover, the legacy flow meter that has been retrofitted, still in place, serves as a functional fallback option.
Pipe infrastructures frequently are old and costly to upgrade, and have defects that are hard to diagnose. For instance, in municipal water supply systems, up to 20% of water is assumed to be lost due to leaks in pipes. Yet pipe leaks are difficult and costly to find, and thus this often is not attempted. Another problem are underreporting water meters, caused by wear or a premature failure of parts under adverse conditions. For instance, turbine flow meters may be affected by sediment build-up near the turbine or the occurrence of back pressure in the pipe, which may lead to gradual or sudden failures.
Both leaks in pipes and underreporting flow meters, are difficult to identify. To determine either condition, one needs to essentially measure throughput in a pipe before and after the location where it is suspected. This typically is infeasible or very costly to do, since it requires an interruption of the pipe envelope and insertion of a measurement instrument into the pipe. Leaks in pipes are often diagnosed by means of analyzing vibration signals. This is a manual, labor intense process, requiring the placement of devices that generate or record sound waves in proximity to pipes at probe points.
Having a pipe system comprehensively equipped with smart devices, capable of capturing measurement data and transmitting them in digital format, allows for large scale data collections, concurrently at many measuring points. Such data might be used for the detection of water leaks or defects in flow meters, correlating measurement data of multiple types, including the rate of throughput and vibration signals. However, smart meters operate on a limited energy budget, as they are frequently not connected to the electrical grid. Designs of such systems for water leak detection need to take into account the constraints set by a limited battery power and computational capacity.